Optical fiber connection system including optical fiber alignment device

ABSTRACT

A self-centering structure ( 300 ) for aligning optical fibers ( 308 ) desired to be optically coupled together is disclosed. The self-centering structure ( 300 ) including a body ( 310 ) having a first end ( 312 ) and a second end ( 314 ). The first end ( 312 ) defines a first opening ( 303 ) and the second end ( 314 ) defines a second opening ( 304 ). The self-centering structure ( 300 ) includes a plurality of groove structures ( 306 ) integrally formed in the body ( 310 ) of the self-centering structure for receiving the optical fibers ( 308 ) and a fiber alignment region ( 305 ) positioned at an intermediate location between the first and second ends ( 312, 314 ) to facilitate centering and alignment of the optical fibers ( 308 ). The self-centering structure ( 300 ) further includes a plurality of cantilever members ( 322 ) arranged and configured on opposing sides of the fiber alignment region ( 305 ). Each of the plurality of cantilever members ( 322 ) are aligned with a respective one of the plurality of groove structures ( 306 ). The plurality of cantilever members ( 322 ) include a first plurality of cantilever members ( 322   a ) adjacent the first end ( 312 ) of the self-centering structure ( 300 ) and a second plurality of cantilever members ( 322   b ) adjacent the second end ( 314 ) of the self-centering structure ( 300 ). The plurality of cantilever members ( 322 ) is flexible and configured for urging the optical fibers ( 308 ) into their respective groove structures ( 306 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is being filed on Aug. 20, 2015, as a PCT InternationalPatent Application and claims priority to U.S. Patent Application Ser.No. 62/052,816 filed on Sep. 19, 2014, and claims priority to U.S.Patent Application Ser. No. 62/092,021 filed on Dec. 15, 2014, thedisclosures of which are incorporated herein by reference in theirentireties.

TECHNICAL FIELD

The present disclosure relates to optical fiber connection systems andto devices and methods for aligning two fibers end-to-end.

BACKGROUND

Modern optical devices and optical communications systems widely usefiber optic cables. Optical fibers are strands of glass fiber processedso that light beams transmitted through the glass fiber are subject tototal internal reflection wherein a large fraction of the incidentintensity of light directed into the fiber is received at the other endof the fiber.

Many approaches to achieve fiber alignment can be found in the priorart, among them are V-grooves and ferrules. Ferrule based alignmentsystems including include ferruled connectors which use cylindricalplugs (referred to as ferrules) that fit within an alignment sleeve(e.g., a cylindrical split sleeve with elastic characteristics) toperform fiber alignment. Precision holes are drilled or molded throughthe centers of the ferrules. Optical fibers are secured (e.g., potted)within the precision holes with polished ends of the optical fiberslocated at end faces of the ferrules. Precise fiber alignment depends onthe accuracy of the central hole of each ferrule. Fiber alignment occurswhen two ferrules are inserted into an alignment sleeve such that theend faces of the ferrules oppose one another and the optical fiberssupported by the ferrules are co-axially aligned with one another.Normally, ferruled connectors use ceramic or metal ferrules in which theprecision center holes are drilled. Disadvantageously, drilling of sucha central hole that is accurate enough for aligning can be difficult. Inaddition, a connector containing a ferrule has very high manufacturingcosts. Therefore looking for adequate alignment solutions containingferrule-less connectors would be more desirable.

V-grooves are commonly used in prior-art ferrule-less fiber opticalignment devices. An example is the V-groove method described in U.S.Pat. No. 6,516,131 used for alignment of optical fiber ends. TheV-groove is uni-directionally or bi-directionally tapered for enablingeasy positioning of the fibers. Optical fibers are pressed into theV-grooves and line contact between the optical fibers and the surfacesof the V-grooves assists in providing precise alignment of the opticalfibers. In one example, two optical fibers desired to be opticallyconnected together are positioned end-to-end within a V-groove such thatthe V-groove functions to co-axially align the optical fibers. End facesof the aligned optical fibers can abut one another.

SUMMARY

One aspect of the present disclosure relates to a device and method foraligning two fibers end-to-end. Co-axial alignment can be providedbetween the optical fibers of two fiber optic connectors so as toprovide an optical coupling between the optical fibers. In such anembodiment, the optical connectors can be ferrule-less opticalconnectors. Co-axial alignment can also be provided between the end ofan optical fiber of a fiber optic cable and a stub end of an opticalfiber supported by a ferrule. In certain embodiments, fiber alignmentdevices in accordance with the principles of the present disclosure canaccurately align optical fiber while using a minimal number of parts toreduce cost and facilitate assembly.

The term “fiber” as used herein relates to a single, opticaltransmission element having a core usually having a diameter of 8-12 μmand a cladding usually having a diameter of 120-130 μm, wherein the coreis the central, light-transmitting region of the fiber, and the claddingis the material surrounding the core to form a guiding structure forlight propagation within the core. The core and cladding can be coatedwith a primary coating usually comprising one or more organic or polymerlayers surrounding the cladding to provide mechanical and environmentalprotection to the light-transmitting region. The primary coating mayhave a diameter ranging e.g. between 200 and 300 μm. The core, claddingand primary coating usually are coated with a secondary coating, aso-called “buffer”, a protective polymer layer without opticalproperties applied over the primary coating. The buffer or secondarycoating usually has a diameter ranging between 300-1100 μm, depending onthe cable manufacturer.

The term “light” as used herein relates to electromagnetic radiation,which comprises a part of the electromagnetic spectrum that isclassified by wavelength into infrared, the visible region, andultraviolet.

Index matching gel can be used with alignment devices in accordance withthe principles of the present disclosure to improve the opticalconnection between the open light transmission paths of the first andsecond optical fibers. The index matching gel preferably has an index ofrefraction that closely approximates that of an optical fiber is used toreduce Fresnel reflection at the surface of the bare optical fiber ends.Without the use of an index-matching material, Fresnel reflections willoccur at the smooth end faces of a fiber and reduce the efficiency ofthe optical connection and thus of the entire optical circuit.

A self-centering structure is provided in accordance with a fiberalignment system to align fibers from ferrule-less connector plugs orother structures. The fibers protruding from the plugs are guided andaligned by a self-centering device, including a cantilever member whichprojects at least partially at an angle toward the fiber axis.

The self-centering devices can be assembled in a module, such aspositioned within a split sleeve or other structure, or held together byother methods, wherein each self-centering device includes at least onecantilever member.

In one example implementation, each self-centering device includes threecantilever members positioned around the fiber axis.

Preferably more than one self-centering device is provided per fiber. Inone implementation, two self-centering structures are provided for eachfiber.

In one example, if the self-centering structures are provided with asingle cantilever member, the cantilever member presses the fiber towarda groove structure, such as a V-groove, or a gap or slot. The V-groovecan be defined by two parallel rods.

In another example, if the self-centering structures are provided withplural cantilever members spaced around the fiber axis, the cantilevermembers press the fiber toward the other one or more cantilever membersto centralize the fiber at the fiber axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a first embodiment in perspective view of a self-centeringstructure for centering two optical fibers;

FIG. 2 is a partial cross-sectional perspective view of theself-centering structure of FIG. 1;

FIG. 3 is a perspective view of a self-centering device of theself-centering structure of FIGS. 1 and 2;

FIG. 4 is a perspective view of the self-centering device of FIG. 3;

FIG. 5 is a sectional view of a portion of the self-centering device ofFIGS. 3 and 4;

FIG. 6 is a second embodiment in perspective view of a self-centeringstructure for centering two optical fibers;

FIG. 7 is a top view of the self-centering structure of FIG. 6;

FIG. 8 is a side view of the self-centering structure of FIG. 6;

FIG. 9 is an end view of the self-centering structure of FIG. 6;

FIG. 10 is a cross-sectional end view of the self-centering structure ofFIG. 6 taken along lines 10-10 of FIG. 8;

FIG. 11 is an exploded perspective view of the self-centering structureof FIG. 6;

FIG. 12 is an end view of a self-centering device of the self-centeringstructure of FIGS. 6-11;

FIG. 13 is an opposite end view of the self-centering device of FIG. 12;

FIG. 14 is a first cross-sectional view of the self-centering device ofFIG. 12 taken along lines 14-14;

FIG. 15 is a second cross-sectional view of the self-centering device ofFIG. 12 taken along lines 15-15;

FIG. 16 is a top view of a fiber optic adapter useable with theself-centering structures of FIGS. 1-15;

FIG. 17 is a cross-sectional side view of the fiber optic adapter ofFIG. 16;

FIG. 18 is a cross-sectional side view of a fiber optic connectoruseable with the fiber optic adapter of FIGS. 16-17;

FIG. 19 is a third embodiment in perspective view of a self-centeringstructure for centering two optical fibers;

FIG. 20 is a top view of a portion of the self-centering device of FIG.19;

FIG. 21 is a side perspective view of FIG. 20;

FIG. 22 is a front perspective view of a portion of the self-centeringdevice of FIG. 19;

FIG. 23 is a top perspective view of FIG. 22;

FIG. 24 is a front view of the self-centering device of FIG. 19;

FIG. 25 is a sectional view of a portion of the self-centering device ofFIG. 19 without the fibers; and

FIG. 26 is a perspective view of the self-centering structure of FIG. 19shown having two parts.

DETAILED DESCRIPTION

A self-centering structure 100, 200 is provided in accordance with afiber alignment construction or system 10 to align fibers fromferrule-less connector plugs 600 or other structures. The fibers 302protruding from the plugs are guided and aligned by a self-centeringdevice 110, 210, including at least one cantilever member 120, 220 whichprojects at least partially at an angle toward the fiber axis 124, 224,and terminates at a distal end 122, 222. The cantilever members 120, 220are flexible to centralize the fiber 302 for alignment with anotherfiber 302. FIGS. 2, 5, and 14 show the angling of the cantilevermembers. Such a construction allows for the funnel shape for fiberfeeding, and for bending to create clamping forces on the fibers. Thealignment construction 10 includes a fiber alignment region 103, 203 atan intermediate location between the first and second ends.

The self-centering structures can be assembled in a module or unit 105,205, such as including a split sleeve 130 or other structure 230,wherein each self-centering structure includes at least one cantilevermember 120, 220. Split sleeve 130 holds the separate parts together toform a single unit with an aligned fiber axis. Structure 230 is a pressfit arrangement of the parts that remain as a single unit, also formaintaining the aligned fiber axis. Each unit 105, 205 includes oppositeends 107, 207.

In one example implementation, each self-centering structure 100includes three cantilever members 120.

Preferably more than one self-centering device 110, 210 is provided perfiber. In one implementation, two self-centering devices 110, 210 areprovided for each fiber.

If the self-centering structures 200 are provided with a singlecantilever member 220, the cantilever member 220 presses the fibertoward a groove structure, such as a V-groove 228, or a gap or slotdefined by two parallel rods 226.

If the self-centering structures 100 are provided with plural cantilevermembers 120, the cantilever members 120 press the fiber toward the otherone or more cantilever members to centralize the fiber.

The self-centering devices 110, 210 each define a funnel shape 160, 260to facilitate entry of the fiber 302 along the fiber axis 124, 224 orfiber alignment axis. The self-centering devices 110, 210 are positionedfront to back in a stack for single fiber alignment (same direction ofprojection of the cantilever members). The pairs of stackedself-centering devices 110, 210 are positioned front to front relativeto the centerline mating plane for alignment of two fibers end to end(opposite direction of projection of the cantilever members).

With the example embodiments showing four self-centering devices, theouter two serve as a pre-alignment structure. The inner two align thetwo mating fibers. At the contact zone, a gap 170, 270 is desiredbetween the opposing cantilever members 120, 220 from oppositeself-centering devices 110, 210. The gap can range from 100 microns to 1millimeter. Less than or equal to 1 millimeter is desired. Less than orequal to 750 microns is more preferred, and less than or equal to 500microns, and even less than 100 microns is useful. The gap avoidsinterference and allows for good fiber alignment. Index matching gels oroils can be used in the self-centering structures 100, 200. Hole 290 canbe used to apply the index matching material.

In the case of self-centering device 110, the component can be made asan integral body 116, including the three cantilever members 120. In thecase of self-centering device 210, the component can be made as anintegral body 216 with the single cantilever member 220, and a passage270. Passage 270 receives the two parallel rods 226 in a press-fitmanner.

Integral bodies 116, 216 can be made from molded materials. Centralpassage 180, 280 through the structures 100, 200 is preferably smallerthan the outer diameter of the fiber. In one example, forces in therange of 0.1-0.2 Newtons can be generated on the fiber 302 for alignmentand centering.

Distal ends 122, 222 of cantilever members 120, 220 include a smallcenter groove 150, 250 to facilitate centering and alignment of thefibers.

The self-centering structures 100, 200 can be used in an adapter 400.Adapter 400 receives at least on connector 600 on each end 402, 404 fordefining a signal path between the two fibers 302 of the two connectors600. The self-centering structures 100, 200 can be placed in alignmentareas 500 within adapter 400. In the example shown, adapter 400 is aduplex adapter for joining two fibers, with each end 402, 404 receivingtwo connectors 600.

Connector 600 is an example connector, such as further shown in PCTPublication WO2013/117598, the disclosure of which is incorporated byreference. Connector 600 includes a connector body 602, and a moveablecover 604. A latch 606 latches the connector 600 to the adapter 400.Fiber 302 is shown protruding from the front end 608 of connector 600.

The optical fiber alignment devices can be incorporated into both endsof a fiber optic adapter. The optical fiber alignment devices can beincorporated into an adapter wherein the fiber optic adapter receives aferrule-less connector on one end and a ferruled connector on anopposite end. The optical fiber alignment devices can also beincorporated into a converter for converting a ferrule-less connectorinto a ferruled connector.

In other examples, it may be desired to include another alignmentstructure for fiber optic ribbon cables. The alignment structure can beused to align each of the optical fibers as part of a process tooptically connect each of the optical fibers precisely to a fiber opticconnector. The optical fibers are held in alignment when provided in theribbon matrix. FIG. 19 shows an example alignment self-centeringstructure 300 in accordance with a fiber ribbon alignment constructionor system to align fibers from ferrule-less connector plugs or otherstructures. In one example, a fiber optic ribbon cable may include aplurality of optical fibers 308. Each of the plurality of optical fibers308 includes a fiber axis 330 and each of the plurality of opticalfibers 308 includes a bare optical fiber and a coating surrounding thebare optical fiber to form an external surface of the optical fiber.

The self-centering structure 300 can be made from molded materials. Theself-centering structure 300 includes a body 310 having a first end 312,a second end 314, a top 316 and a bottom 311. The first end 312 definesa first opening 303 and the second end 314 defines an opposite secondopening 304. The first and second openings 303, 304 each provide foroptical fibers 308 to be centered and oriented in the bottom 311 of theself-centering structure 300. The bottom 311 has a plurality of groovestructures 306 integrally formed, such as a V-grooves, or gaps, orslots. It will be appreciated that the groove structures 306 can includeother groove profiles using various materials and manufacturingprocesses.

FIGS. 20-21 show the groove structures 306 in parallel alignment thatextend along the fiber axis 330. Each of the plurality of optical fibers308 may be inserted through the bottom 311 of the first and secondopenings 303, 304 such that the fibers are disposed within the groovestructures 306 in a substantially uniform orientation to facilitatecentering and alignment of a first plurality of optical fiber 308 a witha second plurality of optical fiber 308 b. In this manner, as anon-limiting example, the self-centering structure 300 provides analignment of the first plurality of optical fibers 308 a in the firstopening 303 to the second plurality of optical fibers 308 b in thesecond opening 304.

As depicted in FIG. 19, twelve optical fibers 308 are aligned in each ofthe first and second openings 303, 304 relative to one another. Thefirst plurality of optical fibers 308 a extend from the first opening303 at the first end 312 into the self-centering structure 300 to alignwith the second plurality of optical fibers 308 b extending from thesecond opening 304 at the second end 314 of the self-centering structure300.

The top 316 of the body 310 of the self-centering structure 300comprises a planar region 318. The planar region 318 contains a recess320 including a plurality of cantilever members 322. In one example, theplurality of cantilever members 322 extend from the planar region 318and project at least partially downward at an angle toward the opticalfibers 308. It will be appreciated that the plurality of cantilevermembers 322 may be configured to press the optical fibers in the grooveswithout being angled down. For example, a cantilever member may includea bump (e.g., projection) that extends from the body of the cantileverto engage the fibers and press the fibers into a respective groove.

Referring again to FIG. 19, a first set of cantilever members 322 a aregenerally on the first end 312 of the self-centering structure 300 andcan extend downwardly in the recess 320 at an angle toward the firstplurality of optical fibers 308 a at the first opening 303. A second setof cantilever members 322 b are generally on the second end 314 of theself-centering structure 300 and can extend downwardly at an angletoward the second plurality of optical fibers 308 b at the secondopening 304. As described above, the arrangement and configuration ofthe first and second plurality of cantilever members 322 a, 322 b mayvary in other embodiments such that they do not angle downward into therecess 320.

In one example, the first set of cantilever members 322 a are flexibleand configured for urging each of the first plurality of optical fibers308 a into their respective groove structures 306 and the second set ofcantilever members 322 b are flexible and configured for urging each ofthe second plurality of optical fibers 308 b into their respectivegroove structures 306. In other words, the first and second sets ofcantilever members 322 a, 322 b respectively align the first and secondplurality of optical fibers 308 a, 308 b to one another.

Referring to FIGS. 22-23, the recess 320 has an open bottom 324 suchthat a fiber alignment region 305 (see FIG. 19) is made visible betweenthe first and second sets of cantilever members 322 a, 322 b. The fiberalignment region 305 can help to facilitate centering and alignment ofthe optical fibers 308 with another optical fiber 308. The cantilevermembers are arranged and configured on opposite sides of the fiberalignment region 305. The cantilever members are shown having one row oneach side of the fiber alignment region 305. It will be appreciated thatother embodiments can include two or more rows on each side of the fiberalignment region 305. The cantilever members 322 are flexible tocentralize the optical fibers 308 for alignment with another opticalfiber 308 in the fiber alignment region 305. FIGS. 23 and 25 show oneconfiguration of the cantilever members 322 being angled downward toallow for bending to create clamping forces on the optical fibers 308while in the groove structures 306 as shown in FIG. 24. It will beappreciated that other arrangements and configurations of the cantilevermembers 322 may be used.

The self-centering structure 300 can be assembled as a single module orunit including the groove structures 306 and cantilever members 322. Theself-centering structure 300 can be made as an integral body includingthe twelve cantilever members 322 and groove structures 306. In otherexamples, a self-centering structure 300 a can include two parts asshown in FIG. 26. A first part 326 including the groove structures 306and a second part 328 including the cantilever members 322. The firstand second parts 326, 328 can be press fit together to form a singleunit with an aligned fiber axis. The cantilever members 322 press thefibers toward the other respective cantilever members 322 to centralizethe fibers.

From the forgoing detailed description, it will be evident thatmodifications and variations can be made without departing from thespirit and scope of the disclosure.

PARTS LIST

-   10 Alignment construction-   100 Self-centering structure-   103 Fiber alignment region-   105 Alignment construction-   107 Ends-   110 Self-centering devices-   116 Integral body-   120 Cantilever member-   122 Distal end-   124 Fiber axis-   130 Split sleeve-   150 Alignment groove-   160 Funnel shape-   170 Gap-   180 Central passage-   203 Fiber alignment region-   205 Unit-   207 Ends-   210 Self-centering devices-   216 Integral body-   220 One cantilever member-   222 Distal end-   224 Fiber axis-   226 Alignment rods-   228 V-groove-   230 Structure-   250 Alignment groove-   260 Funnel shape-   270 Passage-   280 Central passage-   290 Hole-   300 Self-centering structure-   302 Fiber-   303 First opening-   304 Second opening-   305 Fiber alignment region-   306 Groove structure-   308 Optical fibers-   308 a First plurality of optical fibers-   308 b Second plurality of optical fibers-   310 Body-   312 First end-   311 Bottom-   314 Second end-   316 Top-   318 Planar region-   320 Recess-   322 Cantilever members-   322 a First set of cantilever members-   322 b Second set of cantilever members-   324 Open bottom-   326 First part-   328 Second part-   330 Fiber axis-   400 Adapter-   402 End-   404 End-   500 Alignment areas-   600 Connector-   602 Connector body-   604 Moveable cover-   606 Latch-   608 Front end

1. An optical fiber alignment device comprising: an alignmentconstruction including first and second ends, the alignment constructiondefining a fiber axis that extends through the alignment constructionbetween the first and second ends, the alignment construction includinga fiber alignment region at an intermediate location between the firstand second ends; first and second cantilever members for urging thefirst and second fibers toward the fiber axis.
 2. The optical fiberalignment device of claim 1, wherein the alignment device isincorporated into a fiber optic adapter.
 3. The optical fiber alignmentdevice of claim 2, wherein the fiber optic adapter receives aferrule-less connector on one end and a ferruled connector on anopposite end.
 4. The optical fiber alignment device of claim 1, whereinthe alignment device is incorporated into a converter for converting aferrule-less connector into a ferruled connector.
 5. The optical fiberalignment device of claim 1, wherein three first and three secondcantilever members are provided for urging the fiber to an alignmentposition, each of the first cantilever members and each of the secondcantilever members centered about the fiber axis.
 6. The optical fiberalignment device of claim 1, further comprising: first and second fiberalignment rods positioned within the alignment housing, the first andsecond fiber alignment rods cooperating to define a fiber alignmentgroove that extends along the fiber axis, the first and second fiberalignment rods each having rounded ends positioned at the first andsecond ends of the alignment housing.
 7. The optical fiber alignmentdevice of claim 1, wherein each cantilever member includes an alignmentgroove on a distal end.
 8. An optical fiber alignment device comprising:an alignment construction including first and second ends, the alignmentconstruction defining a fiber axis that extends through the alignmentconstruction between the first and second ends, the alignmentconstruction including a fiber alignment region at an intermediatelocation between the first and second ends; a first cantilever memberfor urging the first fiber toward the fiber axis.
 9. The optical fiberalignment device of claim 8, wherein the alignment device isincorporated into a fiber optic adapter.
 10. The optical fiber alignmentdevice of claim 9, wherein the fiber optic adapter receives aferrule-less connector on one end and a ferruled connector on anopposite end.
 11. The optical fiber alignment device of claim 8, whereinthe alignment device is incorporated into a converter for converting aferrule-less connector into a ferruled connector.
 12. The optical fiberalignment device of claim 8, wherein three first and three secondcantilever members are provided for urging the fiber to an alignmentposition, each of the first cantilever members and each of the secondcantilever members centered about the fiber axis.
 13. The optical fiberalignment device of claim 8, further comprising: first and second fiberalignment rods positioned within the alignment housing, the first andsecond fiber alignment rods cooperating to define a fiber alignmentgroove that extends along the fiber axis, the first and second fiberalignment rods each having rounded ends positioned at the first andsecond ends of the alignment housing.
 14. The optical fiber alignmentdevice of claim 8, wherein each cantilever member includes an alignmentgroove on a distal end.
 15. The optical fiber alignment device of claim1, further comprising a plurality of cantilever members at the first andsecond ends.
 16. A self-centering structure for aligning optical fibersdesired to be optically coupled together comprising: a body including afirst end and a second end, wherein the first end defines a firstopening, and the second end defines a second opening; a plurality ofgroove structures integrally formed in the body of the self-centeringstructure for receiving the optical fibers; a fiber alignment regionpositioned at an intermediate location between the first and second endsof the body to facilitate centering and alignment of the optical fibers;and a plurality of cantilever members arranged and configured onopposing sides of the fiber alignment region, each of the plurality ofcantilever members being aligned with a respective one of the pluralityof groove structures; the plurality of cantilever members including afirst set of cantilever members adjacent the first end of theself-centering structure and a second set of cantilever members adjacentthe second end of the self-centering structure; wherein the plurality ofcantilever members are flexible and configured for urging the opticalfibers into their respective groove structures.
 17. The self-centeringstructure of claim 16, wherein the self-centering structure is onesingle module.
 18. The self-centering structure of claim 16, wherein theself-centering structure includes two separate parts.
 19. Theself-centering structure of claim 16, wherein each of the plurality ofcantilever members project at least partially downward at an angletoward the optical fibers.
 20. The self-centering structure of claim 16,wherein each of the plurality of groove structures extend along a fiberaxis.